Dark Energy From The Gravity Vacuum

TL;DR

This paper introduces a novel approach to the cosmological constant problem using nonperturbative quantum gravity with torsional instantons, linking topological charges to dark energy.

Contribution

It presents a new solution to the cosmological constant problem based on torsional instantons in quantum gravity, fixing the Barbero-Immirzi parameter to match the Hubble constant.

Findings

Nonperturbative ground state is stable under quantum fluctuations.

Vacuum angle is fixed by the Hubble constant.

Proposes a link between topological charges and dark energy.

Abstract

We propose a new solution to the cosmological constant problem building on a nonperturbative quantum theory of gravity with torsional instantons. These pseudoparticles, which were recently found to exist in a first order formulation of Giddings-Strominger axionic gravity, carry nontrivial Nieh-Yan topological charge. The nonperturbative ground state as generated due to tunneling effects is shown to be stable under quantum fluctuations. Within this framework, the associated vacuum angle, namely the Barbero-Immirzi topological parameter, gets fixed to a numerical value determined by the Hubble constant.